How to: Homemade shio kombu or kombu no tsukudani

28 Nov 2007 by maki

Kombu, the leathery seaweed that is used to make dashi stock, is packed full of umami. A traditional way to prepare it is as shiokombu (salty kombu) or kombu no tsukudani. Tsukudani is a method of cooking something with soy sauce, sake and/or mirin, and sugar until it’s very dark, quite salty and sweet too. It’s a preserving method, since the salt and sugar greatly increase the keeping qualities of the food.

Kombu no tsukudani can be tucked into the corner of a bento box to add a little variety. It’s also a good onigiri filling. Properly made and stored in the refrigerator, it keeps almost forever.

It does take a while to cook, depending on how tough the kombu is. It’s worth making if you think commercial kombu no tsukudani is too salty or too sweet, or too expensive.

It can be made from unused dry kombu or kombu that’s been used once to make dashi. I’ve given instructions for both.

Kombu no tsukudani or shiokombu

Since kombu comes in all sizes, I’ve given weight amounts here. You can halve the amounts if this seems like too much to make at once.

100g / 3 1/2 oz dry kombu seaweed, ideally one that is thick and covered with a fine whiteish powder

Inspect the kombu - if it has sand or dirt on it (not the natural fine white powdery coating), wash it off. (Nowadays it’s rare to find sand etc. on commercially available kombu, but if you buy it from a local producer or even gather it yourself, you’ll have to deal with that.)

Soak the kombu in water to cover just until it’s soft enough to cut. Drain, making sure the water drips back into whatever you were soaking the kombu in, and cut the kombu into bite-sized pieces.

Put the kombu back in the soaking water and add vinegar. Leave for an hour or more. The kombu should feel a bit slimy at the end of the soaking period. The vinegar helps to tenderize it. Some thicker kinds of kombu may require a longer soak.

Put the kombu and soaking liquid into the heavy pan. Add the other ingredients. Bring up to a simmer then lower the heat - the surface of the liquid should be barely bubbling. Add water if it starts to dry out.

Simmer slowly like this until the kombu is very soft - it should seem almost too soft, since when it cools the kombu will stiffen up a bit. By this point there should be very little liquid in the pan. Taste the kombu, and add a bit more soy sauce or sugar if needed, and simmer some more. When it’s done the kombu will be shiny and caramelized and have a translucent quality, like thin slices of dark caramel or tortoiseshell.

Store, covered, in the refrigerator.

You can optionally add a couple of handfuls of bonito flakes near the end of the cooking process. Mix in well, and let it cook down until it’s almost dry. (Adding bonito flakes will make it no longer vegan of course, since bonito is a fish.)

You can also add red pepper flakes or shichimi (or nanami!) tohgarashi for a bit of spice.

Using pre-used kombu

You can use kombu that was used for making dashi, either the regular kind or the vegetarian version. What I do is to cut up the soaked kombu and store it in a container in the freezer until I have enough to make kombu no tsukudani. There is less umami than in the version made from unused kombu, but it’s still tasty. Here are the seasonings proportions:

1 cup (240ml) of cut-up, defrosted, pre-used kombu

1/2 Tbs. vinegar

Water to cover

1-2 Tbs (or more, to taste) tamari or dark soy sauce

3 Tbs. sake

1 Tbs. mirin

1 Tbs. sugar

About 1/2 tsp. of grated ginger juice.

This will need less soaking time, since it’s already been soaked, and the freezing and de-frosting would have broken down the fibers a bit. Proceed as with the recipe above.

Instant soup from kombu no tsukudani

Put a little homemade or commercial kombu no tsukudani into a mug or small bowl, and add hot water. Optionally add a little julienned fresh ginger. Stir and let sit for a few minutes. It makes an interesting clear soup. (Confession: I used to hate this when I was a kid, but now I rather like it. It may take some getting used to.)

I tried making this dish some months back. Got the recipe from a Japanese cookbook. I had some saved up kombu from making dashi and was looking forward to eating this. The recipe I used suggested cutting the kombu in strips and cooking it with liquid composed of vinegar, soy, mirin and sugar. After cooking it the allotted time, my kombu was still very hard, slimey and smelled somewhat fishy and vinaigry. It wasn’t what I expected and I threw it away.

Thank you for this recipe, I’ve made it a couple of days ago and the results are gone already!
Ever since coming back from Japan last November, I’ve been going through withdrawl: I couldn’t care less for homey-food, give me a bowl of plain Japanese rice anytime and I’ll be happy (I was astonished to find that rice could tast so good and very different from the one we’re used to here). :D
Most of the stuff I brought back was some sort of pickles or tsukudani, possibly hijiki no tsukudani (since I remember the texture to be different from konbu), and two kinds of fish-based ones— iriko and chirimen no tsukudani, perhaps? I’m wondering about making these: do you know if it’s okay to follow the same process as above? Will it work with fresh fish?
I also tried something similar while wandering around Tsukiji market, I think the label read Kingoma Maguro [金ごま まぐろ]. The strange thing is that it didn’t taste like the tuna had been cooked at all.
Anyway, enough rambling.
Thank you for both your Japanese cooking blogs, I find it oddly comforting to read about food I enjoyed so much, and try my hand at making it myself.

If you keep in mind that both items are already pretty salty, and adjust the amount of salt (soy sauce) in the broth, you should be able to follow the basic recipe to make it into tsukudani.

I’ve not heard of the kingoma maguro, but you can also make fresh maguro into tsukudani - just cut into small cubes (less than 1cm or 1/2 inch) and slowly cook in the broth until it’s almost caramelized.

When I was in Japan, my favorite food was definitely onigiri. I got them whenever I needed to fill out a meal or even as a meal unto themselves. Every time I bought them (from convenience stores) there would be two default fillings (they usually came in packs of two). I could easily identify the salmon filling (although a lot of people cheated by dyeing tuna fish pink!) but the second was a mystery until I saw this recipe. Thanks! I must try my hand at it once I can get some kombu ^_^